Mounting Star for a Washing Machine

ABSTRACT

A mounting star stabilizing and rotationally mounting a washing drum of a washing machine. The mounting star comprises at least three arms near the center of the mounting star and a hollow molded body with a box-like open profile. Support points support the mounting star against the rear wall of the washing drum and are arranged at a distance from approximately the mid-length of each arm. The open profile of the arm is made of a pair of surfaces which are non-connected between themselves and are at least similar to a flat rectangle which forms the transversal section of the supports and the short sides thereof are oriented towards the rear wall of the washing drum. Both of the supports are connected by means of a third support of the identical transversal surface from arm to arm, with a support of the other arm.

The invention relates to a mounting star for stabilizing the rear wallof a drum-type component of a washing machine, and for assembly on it,at least three arms of which component are embodied in the center of themounting star and include hollow molded bodies with a box-like, openprofile, and with support points provided at a distance of a length fromthe central axis of the mounting star, preferably to approximately themid-length of each arm, which points serve as a support against the rearwall of the drum-type component.

Such mounting stars for a washing drum are disclosed in DE 14 60 840 A1and DE 24 32 465 A1. Mounting stars with even greater stiffness arerequired for tubs for transmitting greater forces than are required fora washing drum. They are comprised mainly of cast steel, as disclosed inDE 39 27 166 A1 for example, but are becoming dispensable because tubsare increasingly being produced from plastic and the stiffness istherefore becoming a design element of the tub.

In the mounting stars of prior art their high price is the maincriticism, this price resulting from their design as individual moldedcomponents and from the relatively high quantity of material requiredfor them. Moreover, the mounting stars of prior art are relatively heavyand therefore require a correspondingly heavy balancing weight on thefront side of the tubs concerned, which in turn generates higher coststhan necessary.

The object if the invention is therefore to design a mounting star ofthe type already described so that it is capable of saving weight andcosts, with the lowest possible material consumption, for transmittingthe forces acting in washing machines in the region of tubs or washingdrums.

This object is achieved according to the invention in such a manner thatthe open profile of the arms comprises a pair of surfaces which are notconnected together and are at least similar to a flat rectangle, whichsurfaces form the cross-section of supports and are orientated, with oneof their short sides, towards the rear wall of the drum-type component,and that the two supports are each connected, at least at the supportpoints, by a third support with a similar cross-sectional surface fromarm to arm, to a support of the other arms. This lattice structureprovides the best conditions for designing the mounting star with thelowest possible material consumption, yet so that it is so stable thatits weight can be reduced by almost 40% compared to a conventionalmounting star, but with the same force transmitting capacity. This alsoresults in considerable cost savings as far as the other components ofthe washing machine are concerned.

These savings may prove extremely effective if, in a further developmentof the invention, the supports arranged in pairs are connected togetherby means of a latticework. The supports required for the transmission offorces on the drum-type component may then be dimensioned exclusively toachieve this object, whilst their dimensional stability in and relativeto each other is achieved by the latticework, which can be designed in afiligree fashion.

One design has proved to be a particularly well suited furtherdevelopment in which at least the supports arranged in pairs run in anarc shape with bents opposing each other. This already provides thestructure with sufficient stiffness to render further measuressuperfluous.

The above further development is advantageously rendered particularlystable when the neutral fibers of both supports of a pair run throughthe central axis of the mounting star and each of the supports runningthrough the central axis forms part of two arms so that the respectivelyassigned supports of each arm intersect in the central axis.

According to an advantageous further development of the invention theconnection of the adjacent supports of two arms at the support points toa further support, which runs outside the central axis, is thensufficient.

In one variant the arc-shaped supports continue running from the supportpoints with the same curvature in the direction of the arm ends and areconnected to each other at the end points of the arms to produce astable shape of the mounting star arms.

In another variant, in which the arms of the mounting arm areintrinsically even more torsionally stiff, the arc-shaped supportscontinue running from the supports with a greater curvature andintersect to connect to each other before the ends of the arms. Here aparticularly torsionally stiff effect is achieved if the arc-shapedsupports terminate at the ends of the arms at certain distance from eachother and are connected to each other by means of a cross bracket.

In a further variant the supports of each pair are connected to eachother level with the support points by a cross strut. Although the crossstrut may be designed in highly filigree fashion, it provides torsionalstiffness in the main supports of the arms.

For stabilizing the rear wall of a drum, all the arms are advantageouslyfastened to a bearing hub so that each arc running through the centralaxis of the mounting star is arranged at a certain distance from theadjacent arc of the adjacent arm. Because of the shaping of thesupports, this automatically provides a basic shape for a lattice workthat guarantees the dimensional stability of the mounting star.

Correspondingly, the supports of all the arms are connected to eachother, separated by the same fastening distance, with a round for thebearing axis of the washing drum, for stabilizing the rear wall of awashing drum.

A mounting star designed according to the invention has a profile thatis open towards the sides so that all its components are manufacturedfrom a material in the continuous casting process according to a furtheradvantageous embodiment. This method provides the most favorableconditions for low cost mass production of the mounting star.

In order to avoid water or air turbulence in the tub at the profileopenings of a mounting star fitted to the washing drum according to theinvention, which could have a braking influence on the rotation of thewashing drum and could even generate noises, it is proposed, in avariant of a further development of the invention, to seal cavitiesformed by the latticework of the arms on the side facing away from thedrum-type component, at least partially by a cover not participating inthe flow of force from the arms, or at least partially by a sealingcompound not participating in the flow of force from the arms.

The invention is explained in the following with reference to anexemplary example represented in the drawing, in which

FIG. 1 shows a washing machine represented diagrammatically in a sideview,

FIG. 2 shows the view of a mounting star that is still normally used fora washing drum according to the state of the art,

FIG. 3 shows a view of a variant of the lattice structure of a mountingstar designed according to the invention, with sharp ending arms,

FIG. 4 shows a view according to FIG. 3 of another variant with bluntending arms, and

FIG. 5 shows a view of a variant of the mounting star according to FIG.3 with four arms.

FIG. 1 shows a front-loading washing machine in a housing 1, in which anoscillating system 2, includes a tub 3 and a washing drum 4 mountedhorizontally and pivotably therein, which drum can be driven through ashaft journal 5, a pulley 6 and a belt 7 by an electric motor 8, ismounted so that it is suspended on springs 9 and stands on shockabsorbers 10. The tub 3 has on its rear side a mounting star 11 that canonly be seen from one side, in the center of which mounting star islocated a bearing 12 for shaft journal 5 of washing drum 4.

Washing drum 4 is also supported by a mounting star 13 on its rear side,but its center is connected fixedly in terms of rotation to shaftjournal 5 so that washing drum 4 can be rotated inside tub 3concentrically to bearing 12 of the tub.

A three-armed mounting star 13 of prior art is represented in FIG. 2 ina view of its side facing washing drum rear wall 14. Such a mountingstar comprises a continuous aluminum casting whose arms 15 are profiledin a manner that is shown by the section along line of intersectionII-II. The cross-section shows that arms 15 each have five supports 16to 20 which, viewed in cross-section, stand at least approximatelyperpendicular on rear wall 14 of washing drum 4, and lower cords 21 and22 and upper cords 23 and 24 connecting these supports. These elongatedparts of the arms are connected integrally and centrally to each otherand to a round 25 which supports shaft journal 5.

It has now been found that the forces for the rotary transmission andfor balancing gravitational and centrifugal forces on drum 4 are appliedessentially by supports 16 to 20, whilst cords 21 to 24 mainly serve thepurpose of keeping the supports apart at all points and stiffening them.At individual points 26 and 36 to 41 they also serve for fastening andsupport against the rear wall of washing drum 4 and there of course forintroducing the forces. This introduction of forces, however, could alsobe undertaken without problem by supports 16 and 20 alone. Unlike in theexample of mounting star 13 of prior art shown, mounting stars are alsoknown (not shown) which, for each arm, only have two parallel supports,but here these arms have a larger cross-sectional area than in the caseof the mounting star of prior art shown, and are connected to each otherby a lower cord and support, for each support, a flange-like upper cordon the side facing away from the rear wall, which upper cord serves onthe one hand to stiffen the supports and on the other to fasten the rearwall.

In the knowledge of these conditions on the mounting stars of prior art,and in an endeavor to ensure sparing use of materials, the inventionrelies upon new shapes for a mounting star for which exemplaryembodiments are represented in FIGS. 3 to 5. The exemplary embodimentshown in FIG. 3 only contains supports with a cross-section which isvery similar to a narrow rectangle, as is seen in the secondary figureto FIG. 3 representing section III-III through support part 27-2.Sections at other points of the supports show the same shapes.

The mounting star in FIG. 3 is provided, in a known manner, with a round25 for the shaft journal (not shown here), on whose circumstance arefitted supports 27 to 29 at regular intervals. Supports 27 to 29 areuniformly bent, and their neutral fibers 30 to 32 intersect at thecenter of round 25. Two support parts 27-1 and 29-2, 28-1 and 27-2, aswell as 29-1 and 28-2, form a pair of supports which constitute theessential part of an arm 33, 34 and 35 respectively. Supports points 36to 41 are fitted on them approximately centrally along their length, atwhich support points third supports 42 to 44, also arc-shaped, arefitted which provide a mutual support for arms 33 to 35. Cross struts45, 46 and 47 (represented as dotted lines) may be inserted betweensupport points 36 and 37, 38 and 39 and 40 and 41 respectively, toimprove the torsional stiffness of the individual supports on their longsections between round 25 and the arm ends. At their ends the supportsconverge at an acute in pairs and are linked by connecting regions 48 to50 with which they are suitably connected, e.g. by screwing or riveting,to rear wall 14 or other parts of washing drum 4.

According to FIG. 4 (the same components are denoted by the samereference symbols as in FIG. 3), a mounting star according to theinvention may also be designed with blunt ends of arms 33 to 35. Herethe force transmitting ends of supports 27 to 29, two of which intersectin each end section, are again connected to each other by cross brackets51 to 53. Moreover, the third supports 42 to 44 in FIG. 3 are extendedbeyond support points 36, 37 and 38, 39 and 40, 41 as far as connectionregions 48-1, 48-2 and 49-1, 49-2 and 50-1, 50-2. This provides anarrangement that is more resistant to torsional forces. In the exemplaryembodiment in FIG. 4 cross struts 45 to 47, denoted by dotted lines, maybe dispensed with because the points of intersection of supports 27-1with 29-2, 28-1 with 27-2 and 29-1 with 28-2 already provide sufficienttorsional stiffness in supports 27 to 29.

FIG. 5 shows, with reference to an exemplary embodiment with supports ofarms 54 to 57 that converge at an acute angle, that a four-arm mountingstar can also be designed according to the same principles as in FIG. 3.The principles of a three-arm variant disclosed in FIG. 4 can betransferred directly to a four-arm variant (without being shown ingreater detail here). Arms 54 to 57, assumed to be rather wide, may beof a narrower design by sacrificing the uniformity of the curvatures ofthe bends. Here the bends of the supports would initially be bent at agreater angle from round 25 and become flatter towards the tip. However,the bend may also lead to the intersection of the supports, similar tothe variant according to FIG. 4, in a further tight curvature. Theprinciples of this variant would be at least partially applied here.

The arc-shaped supports 27 to 29 and 42 to 44 have proved the best fortransmitting and transferring the forces generated. If otherrequirements necessitate this, however, the supports may also havesmaller curvatures, or may even be constructed at least approximatelystraight. However, further support parts in a lattice-type arrangementare required, which means that the weight advantage that can be achievedwith the exemplary embodiments represented and optimized is partiallylost again. However, there is still a significant advantage over themounting stars of prior art already represented.

To ensure that the open lattice structures do not lead to water or airturbulence during washing (foaming) or of air (braking of the drumduring spinning) when a mounting star according to the invention is usedon a washing drum, the openings of the structures can be sealed by amethod not shown in further detail, completely or partially on the sidefacing away from the rear wall of the washing drum by a cover or fillingnot participating in the flow of forces from the arms. For example, acovering may be provided by a molded skin of the same material as thesupports, or by another material which is connected to the supports byother means, e.g. by gluing. For example, filling may be achieved byfoaming the cavities.

1-14. (canceled)
 15. A mounting star for stabilizing a rear wall of a rotating drum of a washing machine, and for assembly on the said rear wall, the mounting star comprising: at least three arms extending from a center of the mounting star and including hollow molded bodies with a box-like, open profile; support points provided at a distance from approximately a mid-length point of each arm and supporting against the rear wall of the drum; wherein the open profile of the arms includes a pair of surfaces that are not connected together and are similar to a flat rectangle, the pair of surfaces forming the cross-section of supports and are orientated with a short side towards the rear wall of the drum, the two supports being connected, at least at the support points, by a third support with a similar cross-sectional area from arm to arm, to a support of the other arms.
 16. The mounting star according to claim 15, wherein the supports arranged in pairs are connected to each other by a latticework.
 17. The mounting star according to claim 15, wherein at least the supports arranged in pairs run in an arc shape with bends opposing each other.
 18. The mounting star according to claim 17, wherein neutral fibers of both supports of a pair run through the central axis and each of the supports running through the central axis forms part of two arms, so that the respectively assigned supports of each arm intersect in the central axis.
 19. The mounting star according to claim 16, wherein the adjacent supports of two arms are connected at the support points to a further support which runs outside the central axis.
 20. The mounting star according to claim 19, wherein the arc-shaped supports continue to run from the supporting points with the same curvature in the direction of the arm ends and are connected to each other at the end points of the arms.
 21. The mounting star according to claim 19, wherein the arc-shaped supports continue to run from the support points with a tighter curvature and intersect before the ends of the arms so that they connect to each other.
 22. The mounting star according to claim 21, wherein the arc-shaped supports terminate at the ends of the arms at a certain distance from each other and are connected to each other by means of a cross bracket.
 23. The mounting star according to claim 15, wherein the supports of each pair are connected to each other level with the support points by a cross strut.
 24. The mounting star according to claim 23, wherein all the arms are secured to a bearing hub so that each arc running through the central axis of the mounting star is arranged at a certain distance from the adjacent arc of the adjacent arm.
 25. The mounting star according to claim 23, wherein the supports of all the arms are connected to a round for a bearing journal of the washing drum with the same fastening distance.
 26. The mounting star according to claim 24, wherein all its components are manufactured from a material in the continuous casting process.
 27. The mounting star according to claim 24, wherein the cavities formed by the lattice structure of the arms are sealed on the side facing away from the drum at least partially by a cover not participating in the flow of forces from the arms.
 28. The mounting star according to claim 24, wherein the cavities formed by the lattice structure of the arms are sealed at least partially by a sealing compound not participating in the flow of forces from the arms.
 29. A washing machine comprising: a housing; a tub disposed within the housing; a drum having a rear wall and being disposed within the tub and mounted for rotation with respect to the tub; a mounting star coupled to the rear wall of the drum and comprising: at least three arms extending from a center of the mounting star and including hollow molded bodies with a box-like, open profile; support points provided at a distance from approximately a mid-length point of each arm and supporting against the rear wall of the drum; and wherein the open profile of the arms includes a pair of surfaces that are not connected together and are similar to a flat rectangle, the pair of surfaces forming the cross-section of supports and are orientated with a short side towards the rear wall of the drum, the two supports being connected, at least at the support points, by a third support with a similar cross-sectional area from arm to arm, to a support of the other arms.
 30. The washing machine according to claim 29, wherein the supports arranged in pairs run in an arc shape with bends opposing each other and are connected to each other by a latticework.
 31. The washing machine according to claim 30, wherein the adjacent supports of two arms are connected at the support points to a further support which runs outside the central axis.
 32. The washing machine according to claim 30, wherein the arc-shaped supports continue to run from the supporting points with the same curvature in the direction of the arm ends and are connected to each other at the end points of the arms.
 33. The washing machine according to claim 29, wherein the supports of each pair are connected to each other level with the support points by a cross strut.
 34. The washing machine according to claim 29, wherein the supports of all the arms are connected to a round for a bearing journal of the drum with the same fastening distance. 